1. Field of the Invention
The present invention generally relates to movable body position control devices and stage devices using the movable body position control devices. More particularly, the present invention relates to a movable body position control device and stage device using the movable body position control device whereby rotational action of a movable body and change of a moving speed due to disturbance when both ends of the movable body (stage) are translated in a single direction are prevented.
2. Description of the Related Art
Movable body position control devices configured to control positions of movable bodies are provided to devices called stage devices, for example. Furthermore, there is a gantry moving type stage device in these devices. In this gantry moving type stage device, a gate type movable body (Y stage) moves above a substrate held on a table at a constant speed. See, for example, Japanese Laid-Open Patent Application Publication No. 2002-200450.
In addition, the above-mentioned movable body (Y stage) is extended in a direction (X direction) perpendicular to a moving direction (Y direction). Both end parts of the movable body (Y stage) are movably supported by a pair of a guide members as the movable body (Y stage) straddles the substrate. A moving position of the movable body (Y stage) is detected by a pair of linear scales (position detector). The both end parts of the movable body are driven in the moving direction by a pair of linear motors (driving part).
Corresponding to demands of users, various jigs such as a coating nozzle configured to coat chemical liquid on a surface of the substrate or a sensor configured to inspect the surface of the substrate are installed in the movable body (Y stage). Thus, the movable body (Y stage) is required to have a stable moving speed or moving control with higher precision.
Because of this, the pair of the linear motors is controlled by a feed back system control device configured to simultaneously control driving forces of two points so that the movable body moves at a constant speed based on a detection signal from the pair of the linear scales.
In the related art device, while the moving position of the movable body (Y stage) is detected by the pair of the linear scales, the driving force is controlled by the pair of the linear motors. In this case, various disturbances are input to the movable body. As a result of this, the moving speeds of the both end parts of the movable body are not constant because of vibration or change of a load due to the disturbance, and the movable body leans against a direction perpendicular to the moving direction so that a rotational force whose center is an axis in a direction perpendicular to the movable body is generated.
For example, a torque change (torque ripple) of the linear motor, a load change of a cable bearing configured to guide a cable connected to a coil of the linear motor provided to the movable body, vibration transmitted from a floor, or the like may correspond to the disturbance being input to the movable body. Therefore, the disturbance is not always input to the both end parts of the movable body. Depending on conditions such as the moving speed or the moving position, the load being input or the vibration may be changed.
In a case where such a disturbance is input, it is difficult to stabilize the moving speed that is changed due to the disturbance at a moment by the feed back control. It takes time to attenuate the change due to the disturbance. Therefore, it is difficult to make highly precise movements of the movable body to achieve such as film thickness precision applied by the coating nozzle or sensing precision of the sensor.
In addition, as a driving force control method for controlling the change due to the disturbance, development of a control device using a disturbance observer (disturbance state observer) is now under development. However, in a case of the method for estimating the disturbance so that a translational action (movement) of the movable body is controlled, for example, if the rotational force is applied to the movable body due to change of the load or the like so that the movable body leans, the movable body may be translated even in the state where the movable body leans.